At first glance, the title hero of Mozart’s opera Idomeneo seems a tragic figure, entrapped by an evil fate. At a moment of mortal danger he makes a vow to sacrifice to Neptune the first person he meets, should he be allowed to return home safely – but that person turns out to be his son, whom he dearly loves. Yet neither Giovanni Battista Varesco’s libretto nor Mozart’s music offers a straightforward interpretation of the tale. This situates them in a tradition going back to antiquity, in which the heroes of yore were subjected to intense criticism, no matter how much they might also be admired.

The oldest traces of Idomeneus, the warrior of the Trojan War, are found in Homer’s Iliad. Idomeneus belongs to the first group of great Greek heroes who besieged the city. As the King of Crete he leads a considerable contingent of 80 ships to war against Troy. He is of advanced age, but like Achilles he is merciless in battle and an expert in the art of man-to-man combat.

For the Greeks, the Iliad and the Odyssey described the foundations of their community and were thus part of a historical continuum in which they also situated their own experiences. Initially, this stance was unproblematical, for when the Iliad was composed it reflected the self-image of the aristocrats before whom its verses were read. When the Iliad and the Odyssey took on their final literary form in the course of the 7th and 6th centuries BC, the Greek world was in the midst of major upheaval. Kingly rule had been replaced by other political forms – sovereignty shared by several aristocrats, or democracy. These changes made kingship obsolete, and rule by a single man was now regarded as ‘tyranny’ in the worst sense of the word.

There was something else, too: as the shape of the state changed and a new political life and self-awareness emerged, citizens felt able to ponder the position of the gods and their role. As early as the 6th century BC, scholars were confidently asserting that the gods were an invention of man, and that the monsters that figured in the old stories were just imaginary constructions. People began to tell their old stories in different ways.

The consequences of Idomeneus’ vow to Neptune, for example, was retold in two quite different versions. In the first, Idomeneus sacrifices his son but is then driven out by the people of Crete, so appalled are they by his barbaric behaviour. In the second, he intends to kill his son but does not do the deed and consequently plague breaks out. As the guilty party, the godless Idomeneus is compelled to leave the island and thus loses his throne.

The first variant was the great interest in the Age of Enlightenment. Here, Idomeneus is a brutal warrior who accepts the necessity of killing his own son in order to maintain his rule. The Cretan people, however, are no longer willing to tolerate such a violent act and so drive out their king. The people have as little fear of Neptune the monstrous macho god as they have sympathy for Idomeneus’ behaviour – which is why he has to lose his throne.

His people expect him to fight against the god’s demand, for they see it as an expression of an outmoded value system. But it is this system that Idomeneus himself still wishes to uphold. This tale reflects a dual process of emancipation – one that frees us from both our bondage to the gods, and the inappropriate self-interests of a ruling class ready and willing to commit the worst atrocities to maintain its position.

Translated by Chris Walton.

This is an extract from Martin Zimmermann's article 'Between Violence and Lies' in The Royal Opera's programme book, available during performances and from the ROH Shop.

Operas have long expressed criticism of war and conflict. The hero of Mozart’s La clemenza di Tito (1791) is determined to avoid tyranny at all cost. Verdi gives the title character in Simon Boccanegra (1857, rev. 1881) an ardent plea for peace, while Aida (1871) negatively portrays the Egyptians as brutal warmongers in contrast to the peaceful Ethiopians. Richard Strauss’s Friedenstag (1938) had such a clear anti-war message that the Nazis banned it, while Prokofiev explored the misery of the Napoleonic Wars in War and Peace (1943). Following the horrors of World War II, opera increasingly became a way in which composers – including the dedicated pacifists Tippett and Britten – could explore their political and moral convictions.

In King Priam (1962) Tippett uses the story of the Trojan War to explore the far-reaching effects of personal decisions. All the choices made in the first act of the opera – such as Priam abandoning his baby son Paris and years later bringing him home again, and Paris eloping with Helen – have tragic consequences. But could there ever have been a ‘right choice’? In a significant departure from Ancient Greek myth Tippett downplays the role of the gods – his human characters are independent, and their decisions their own.

In another contrast to his main source the Iliad, Tippett focuses on the trauma of war away from the battlefield, particularly on the sufferings of the ageing King Priam. Act II depicts the brutality of war through a gruesome, harshly-scored trio in which Priam, Hector and Paris gloat over the supposed death of Achilles. Act III movingly explores the terror of the Trojan women as their men fall in battle, and Priam’s grief as he begs Achilles for the body of his son Hector. The final scene, as Priam resigns himself to death, drives home the futility of war.

Britten was as firm a pacifist as Tippett, and wrote several openly anti-war works. Arguably his most famous is the War Requiem (written like King Priam for the consecration of Coventry Cathedral in 1962), which makes poignant use of the poetry of Wilfred Owen, interwoven with the Latin Requiem Mass. Criticism of war also features in several of Britten’s operas, most explicitly Owen Wingrave (a television opera first broadcast in 1971 and first performed onstage in 1974). Owen is expected to follow family tradition and join the army, but rejects a military career, and tells his grandfather General Sir Philip that he would make war a criminal offence. The harsh military music associated with the older Wingraves contrasts with Owen’s ardent defence of pacifism – culminating in his radiant Act II Peace Aria, where he declares ‘in peace I have found my image, I have found myself’. But Owen is denied a happy end when the ghosts of his ancestors take their revenge on him.

Britten and Tippett have not been the only composers to take an anti-war stance. Henze’s pacifism is reflected in his operas Der Prinz von Homburg (1958, about a prince who prefers love to his military duties), The English Cat(1980–83, a humorous work about a group of pacifist cats) and his re-workings of Greek tragedies in The Bassarids (1964–5) and Phaedra (2007). Philip Glass’s hugely popular Satyagraha (1979) explores Gandhi’s concept of non-violent resistance to injustice, while his Appomattox (2007) depicts the horrendous brutality of the American Civil War. Mark-Anthony Turnage turned to Sean O’Casey’s fiercely pacifist play on the tragedy of World War I for The Silver Tassie (2000). And John Adams has explored totalitarianism in Nixon in China (1987), terrorism in The Death of Klinghoffer (1991) and the horrors of nuclear warfare in Doctor Atomic (2005). In our politically volatile times, the message of non-violence in operas seems ever more relevant.

English Touring Opera performs King Priam in the Linbury Studio Theatre 13–22 February 2014. Tickets are currently sold out, but returns may become available.